The invention relates to a process for scheduling a service stop for a machine. It may be applied especially within the fields of vehicles, vehicle subassemblies such as vehicle engines, construction equipment machines, and industrial engines in general.
Up to date, vehicle service is most often performed according to a preventive process. From its first date of operation a vehicle is supposed to be serviced at regular intervals which are predefined by the vehicle manufacturer. Usually, those intervals are defined in terms of a certain distance which the vehicle can travel between two planned service stops, and sometimes in terms of a maximum time interval between such two stops. The intervals could also be defined as a function of operating time of the vehicle or of one of its sub-parts, such as the engine operating hours. At each of these planned service stops, the service team is supposed to replace, to readjust or at least to check a list of vehicle components. The list of components is established according to a predefined service interval specification for each service operation. Of course, such a predefined service scheduling is devised so that service operations are grouped to be performed at common service stops to minimize the numbers of stops for the vehicle.
One problem of this method is that it does not take into account what has really happened in the lifetime of the vehicle. Indeed, in reality, the vehicle may have experienced breakdowns necessitating the premature performance of one or several service operations. To the contrary, some of the planned service operations may have been delayed, for good or bad reasons, compared to their timing in the predefined service scheduling. In both cases, it becomes necessary to deviate from that predefined service scheduling to still comply with the predefined service interval specifications for those operations which have been performed out of the predefined schedule. When such deviations concern only a very limited number of service operations, it is possible to handle this quite easily, but when the number of such deviations rise, which is inevitable when the vehicle ages or when the vehicle is complex and has a very comprehensive preventive service scheduling, those deviations become very complex to handle properly. A usual consequence is then to perform certain service operations too early, which leads to an added cost, or too late, which will increase the risk of vehicle malfunction. In order to minimize those two consequences, it is then necessary to provide additional stops between the predefined service stops. This has of course the downside of reducing the vehicle uptime, which is the time where the vehicle is fully available to perform the operation it is designed for.
In document US2005/0080525, it is disclosed an improved process for determining the time and extent of service operations. According to this process, the service scheduling is constantly updated and can therefore take into account the vehicle's history in terms of service operation. The process described in that document monitors a series of components for which a service interval is specified. Those service intervals are specified with an ending window having a minimum and a maximum end point. When a service stop is to be performed, the process monitors what arc the service operations for which the ending window will occur within a time frame. That time frame is defined as starting when the earliest maximum end point will be reached for the set of monitored service operations. The process also provides for setting a minimal interval between the next stop and a subsequent stop in order to determine which service operations are to be performed within the next service stop or within the subsequent stop. This process has therefore the advantage of updating an initial service scheduling, allowing to take into account the history of unplanned service operations previously performed on a given vehicle.
Nevertheless, there is still room for improving the way service scheduling can be updated, in view of minimizing the risk of vehicle malfunction without performing unnecessary preventive service operations.
According to an aspect of the present invention a process is provided for updating the scheduling of a service stop for a machine, comprising the step of determining, for at least one service operation, a service occurrence specification, characterized in that it comprises the step of monitoring the machine's usage severity and in that it comprises the step of setting an earliest occurrence point and a latest occurrence point for the service occurrence specification which are determined according to the machine usage severity monitored during a monitoring interval.
In an aspect of the invention, the occurrence specification can be the end of a service interval specification.